If you really want Lightroom 5 then you will have to find an upgrade to purchase from a third-party seller such as B&H Photo or Amazon.com. Adobe will only sell the current version which is Lightroom 6. When you install an upgrade, the new version will create a new catalog in the new catalog format. That catalog will contain all of your images and all of the work you have done. My presets were still in the new catalog.

The upgrade to LR 6 via the Adobe web site is 79 US Dollars (you'll have to check the price yourself if you live in another country). Go to Products and scroll down to LR6, click on Buy, change "Full" to "Upgrade"

I don't know what the price for LR5 from other re-sellers is, you should be able to find that out easily.